Category: Structure & materials
Prepared by Eng. Ahmed Fathy, Projects Manager ·
Definition
Soil bearing capacity is the highest pressure the soil can take under a foundation without shear failure or excess settlement. It comes from the soil investigation report, and the column load is divided by it to size the footing.
Why it matters on a project
It is the first number a structural designer needs. Assuming it without testing can give small footings that settle, or large ones that waste concrete and steel.
Worked example
A 900 kN column on soil of 150 kN/m²: area = 900 ÷ 150 = 6 m², a footing about 2.45 × 2.45 m before adding the footing and backfill weight, which the designer then adds.
Common mistake
Designing villa foundations with a value copied from a neighbouring plot instead of testing the site itself.
Frequently asked questions
Where do I get the bearing capacity?
From the soil investigation report prepared by an accredited lab for the site.
Can I build without a soil test?
It is not advisable, and many authorities require it for the permit.
Related terms
- Soil investigation reportThe borehole study on which the foundations are designed.
- Footings (foundations)Structural elements that transfer the building loads to the soil.
- Raft foundationA single reinforced concrete slab foundation under the whole building.
- Pile foundationDeep concrete columns that carry loads down to firm soil.
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